检索结果-南通市图书馆

A hybrid machine learning optimization algorithm for multivariable pore pressure prediction

Petroleum Science 2024年第1期21卷 535-550页

作者： Song Deng Hao-Yu Pan Hai-Ge Wang shou-kun xu Xiao-Peng Yan Chao-Wei Li Ming-Guo Peng Hao-Ping Peng Lin Shi Meng Cui Fei Zhao School of Petroleum and Natural Gas Engineering Changzhou UniversityChangzhou213164JiangsuChina Tubular Goods Research Institute of CNPC Beijing102249China CNPC Engineering Technology R&D Company Limited Beijing102206China

Pore pressure is essential data in drilling design,and its accurate prediction is necessary to ensure drilling safety and improve drilling *** methods for predicting pore pressure are limited when forming particular structures and *** this paper,a machine learning algorithm and effective stress theorem are used to establish the transformation model between rock physical parameters and pore *** study collects data from three *** 1 had 881 data sets for model training,and Wells 2 and 3 had 538 and 464 data sets for model *** this paper,support vector machine(SVM),random forest(RF),extreme gradient boosting(XGB),and multilayer perceptron(MLP)are selected as the machine learning algorithms for pore pressure *** addition,this paper uses the grey wolf optimization(GWO)algorithm,particle swarm optimization(PSO)algorithm,sparrow search algorithm(SSA),and bat algorithm(BA)to establish a hybrid machine learning optimization algorithm,and proposes an improved grey wolf optimization(IGWO)*** IGWO-MLP model obtained the minimum root mean square error(RMSE)by using the 5-fold cross-validation method for the training *** the pore pressure data in Well 2 and Well 3,the coefficients of determination(R^(2))of SVM,RF,XGB,and MLP are 0.9930 and 0.9446,0.9943 and 0.9472,0.9945 and 0.9488,0.9949 and *** achieves optimal performance on both training and test data,and the MLP model shows a high degree of *** indicates that the IGWO-MLP is an excellent predictor of pore pressure and can be used to predict pore pressure.

关键词： Pore pressure Grey wolf optimization Multilayer perceptron Effective stress Machine learning

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

3D cluster members and near-infrared distance of open cluster NGC 6819

引用

Research in Astronomy and Astrophysics 2015年第12期15卷 2193-2203页

作者： Xin-Hua Gao shou-kun xu Li Chen School of Information Science and Engineering Changzhou University Shanghai Astronomical Observatory Chinese Academy of Sciences

In order to obtain clean members of the open cluster NGC 6819, the proper motions and radial velocities of 1691 stars are used to construct a three-dimensional （3D） velocity space. Based on the DBSCAN clustering algorithm, 537 3D cluster members are obtained. From the 537 3D cluster members, the average radial velocity and absolute proper motion of the cluster are Vr = ＋2.30 ±0.04 km s-1 and （PMRA, PMDec） = （-2.5 ±0.5, -4.3 ± 0.5） mas yr-1, respectively. The proper motions, radial velocities, spatial positions and color-magnitude diagram of the 537 3D members indicate that our membership determination is effective. Among the 537 3D cluster members, 15 red clump giants can be easily identified by eye and are used as reliable standard candles for the distance estimate of the cluster. The distance modulus of the cluster is determined to be （m - M）0 -- 11.86 ± 0.05 mag （2355 ±54 pc）, which is quite consistent with published values. The uncertainty of our distance mod- ulus is dominated by the intrinsic dispersion in the luminosities of red clump giants （--0.04 mag）.

关键词： open clusters and associations: individual (NGC 6819) -- Hertzsprung-Russell and C-M diagrams -- stars: kinematics and dynamics -- stars: distances

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Discovery of high-velocity EHB stars in the globular cluster ωCentauri(NGC 5139)

引用

Research in Astronomy and Astrophysics 2015年第10期15卷 1639-1646页

作者： Xin-Hua Gao shou-kun xu Li Chen School of Information Science and Engineering Changzhou University Shanghai Astronomical Observatory Chinese Academy of Sciences

Abstract We report the discovery of 45 high-velocity extreme horizontal branch （EHB） stars in the globular cluster Omega Centauri （NGC 5139）. The tangential ve- locities of these EHB stars are determined to be in the range 93-313 km s^-1, with an average uncertainty of -27 km s^-1. The central escape velocity of the cluster is determined to be in the range 60~105 km s^-1. These EHB stars are significantly more concentrated toward the cluster core compared with other cluster members. The formation mechanisms of these EHB stars are discussed. Our conclusions can be sum- marized as follows：（1） A comparison of the tangential velocities of these EHB stars to the central escape velocity of the cluster shows that most if not all of these EHB stars are unbound to the cluster; （2） These EHB stars obtained high velocities in the central cluster region no longer than - 1 Myr ago and may be subsequently ejected from the cluster in the next -1 Myr; （3） If the progenitors of these EHB stars were single stars, then they may have experienced a fast mass-loss process. If the progen- itors were in close binaries, then they may have formed through disruptions by the intermediate-mass black hole in the cluster center.

关键词： Galaxy: globular clusters: individual: ω Cen (NGC 5139) -- stars:Hertzsprung-Russell and C-M diagrams -- stars: kinematics and dynamics -- stars:binaries (including multiple): close

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Optimizing evasive maneuvering of planes using a flight quality driven model

引用

Science China(Information Sciences) 2024年第3期67卷 197-208页

作者： Chang LIU Shaoshan SUN Chenggang TAO Yingxin shou Bin xu School of Automation Northwestern Polytechnical University Chengdu Aircraft Design & Research Institute of AVIC

This paper investigates the optimal evasive maneuver for a plane to avoid an incoming missile. To accurately model the system dynamics while improving computational efficiency, a simplified plane model based on flight quality is established. A missile model with proportional guidance is also *** problem of determining the optimal evasion plane maneuver is formulated. The Gauss pseudospectral method(GPM) is proposed as a solution to find the optimal maneuver. The optimized maneuver is validated by testing it on a high-fidelity 6-degree-of-freedom(6-DOF) model, which demonstrates the effectiveness of the proposed simplified plane model. The Monte Carlo method is employed to evaluate the capability of the plane to evade missiles in various scenarios and elucidate general principles for successful evasion.

关键词： optimal maneuver flying quality evasive strategy pursuit-evasion game air-to-air combat

来源：

同方期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Electrochemical radical-polar crossover:a radical approach to polar chemistry

引用

Science China Chemistry 2024年第2期67卷 450-470页

作者： Zhoumei Tan Haonan Zhang kun xu Chengchu Zeng Faculty of Environment and Life Beijing University of TechnologyBeijing100124China

Radical-polar crossover(RPC) reaction bridges the gap between one-and two-electron reactivities,thus providing an ideal solution to overcome the limitations of both radical and polar *** this manifold,organic electrochemistry provides a uniquely facile strategy to access a diverse array of radical intermediates,thus broadening the chemical space of the RPC *** review highlights the synthetic advances in the field of electrochemical RPC reactions since 2020,with an emphasis on the substrate scope,reaction limitation and mechanistic *** related RPC reactions are categorized as netoxidative,net-reductive,or redox neutral transformations.

关键词： electrosynthesis radical-polar crossover radical chemistry polar chemistry alkene functionalization

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Improving the accuracy of precipitation estimates in a typical inland arid area of China using a dynamic Bayesian model averaging approach

引用

Journal of Arid Land 2024年第3期16卷 331-354页

作者： xu Wenjie DING Jianli BAO Qingling WANG Jinjie xu kun College of Geography and Remote Sensing Sciences Xinjiang UniversityUrumqi 830017China Key Laboratory of Smart City and Environment Modelling of Higher Education Institute Xinjiang UniversityUrumqi 830017China

Xinjiang Uygur Autonomous Region is a typical inland arid area in China with a sparse and uneven distribution of meteorological stations,limited access to precipitation data,and significant water *** and integrating precipitation datasets from different sources to accurately characterize precipitation patterns has become a challenge to provide more accurate and alternative precipitation information for the region,which can even improve the performance of hydrological *** study evaluated the applicability of widely used five satellite-based precipitation products(Climate Hazards Group InfraRed Precipitation with Station(CHIRPS),China Meteorological Forcing Dataset(CMFD),Climate Prediction Center morphing method(CMORPH),Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record(PERSIANN-CDR),and Tropical Rainfall Measuring Mission Multi-satellite Precipitation Analysis(TMPA))and a reanalysis precipitation dataset(ECMWF Reanalysis v5-Land Dataset(ERA5-Land))in Xinjiang using ground-based observational precipitation data from a limited number of meteorological *** on this assessment,we proposed a framework that integrated different precipitation datasets with varying spatial resolutions using a dynamic Bayesian model averaging(DBMA)approach,the expectation-maximization method,and the ordinary Kriging interpolation *** daily precipitation data merged using the DBMA approach exhibited distinct spatiotemporal variability,with an outstanding performance,as indicated by low root mean square error(RMSE=1.40 mm/d)and high Person's correlation coefficient(CC=0.67).Compared with the traditional simple model averaging(SMA)and individual product data,although the DBMA-fused precipitation data were slightly lower than the best precipitation product(CMFD),the overall performance of DBMA was more *** error analysis between DBMA-fused precipitation dataset and the more advanced Inte

关键词： precipitation estimates satellite-based and reanalysis precipitation dynamic Bayesian model averaging streamflow simulation Ebinur Lake Basin Xinjiang

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Theoretical and numerical research on the dynamic launch response of carbon fiber composite cartridges

引用

Defence Technology（防务技术） 2024年第3期33卷 426-436页

作者： Ruijie Zhang Hui xu Chenlei Huang kun Liu Zhilin Wu School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094JiangsuChina

Understanding the dynamic response of composite material cartridges during the firing process is of great significance for improving their reliability and safety.A theoretical model describing the dynamic response of composite material cartridges is established based on the thick-walled cylinder theory and rate-dependent constitutive model of composite *** correctness of the theoretical model is validated through finite element simulations of cartridge *** influence of chamber pressure and cartridge wall thickness on the cartridge's deformation process and stress distribution is *** results indicate that the primary deformation of composite material cartridges inside the chamber is elastic *** to metal cartridges,composite material cartridges require higher pressure for touching-chamber and are more prone to developing gaps after unloading to ensure smooth *** the deformation process,the touching-chamber behavior of the cartridge can improve the stress *** the same chamber pressure,the touching-chamber behavior can reduce the circumferential stress by approximately 30%.The inner wall surface of the cartridge is a critical area that requires *** touching-chamber behavior can be facilitated by appropriately reducing the cartridge wall thickness while ensuring overall *** study can provide guidance for the optimization design of composite material cartridges.

关键词： Composite material cartridges Dynamic response Thick-walled cylinder theory Finite element simulation Toughing-chamber behavior

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Low-resolution Kramers-Kronig detection system with error-feedback noise shaping

引用

Science China(Information Sciences) 2024年第5期67卷 259-269页

作者： Xiangyong DONG Zhenming YU Hongyu HUANG Kaixuan SUN kun xu State Key Laboratory of Information Photonics and Optical Communications Beijing University of Posts and Telecommunications

In this paper, we investigated the effects of error-feedback noise shaping(EFNS) on a lowresolution Kramers-Kronig(KK) detection system for the first time. Both 16-ary quadrature amplitude modulation(16-QAM) and 64-ary quadrature amplitude modulation(64-QAM) were considered in the experiment. The carrier tone was added on the transmitter side using the virtual carrier-assisted single sideband(VCA-SSB) method to meet the minimum phase(MP) condition. Under the MP condition, KK detection only needs the intensity of the optical signal to be detected by one photodiode(PD) to retrieve the phase information. However, the virtual carrier tone increases the carrier-to-signal power ratio(CSPR), which results in a high peak-to-average power ratio(PAPR) at the transmitter, causing an increase in quantization noise. To mitigate quantization noise in the low-resolution KK detection system, EFNS was applied. The application of EFNS increased the optimal CSPR of the KK detection system and improved receiver sensitivity. Using a 4-bit DAC and the EFNS, 80 km transmission was achieved in the 60-Gbit/s 64-QAM KK detection system.

关键词： optical fiber communications Kramers-Kronig receiver error-feedback noise shaping quantization noise carrier-to-signal power ratio

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Heat distribution model under hydrogen-rich low-carbon conditions in blast furnace

引用

Journal of Iron and Steel Research(International) 2024年第3期31卷 584-594页

作者： Gang Wang Jun xu kun He Zhong-ping Zou Hao Bai School of Metallurgy and Ecological Engineering University of Science and Technology BeijingBeijing 100083China CISDI Low-Carbon Blast Furnace Research Office MCC Low-Carbon Technology Research InstituteChongqing 401122China

Low carbon development of blast furnaces is one of the key technological directions in the current development of *** to the differences in the physical and chemical properties of hydrogen and carbon,hydrogen-rich media entering a blast furnace will change the heat distribution,thus affecting the stability of ***,a heat distribution model was proposed to study the temperature distribution in a blast furnace,simultaneously considering gas-solid heat exchange,slag and iron melting,and chemical *** model was used to analyze the temperature distribution of a 2300 m^(3) blast furnace and was verified via comparison with actual production ***,the effects of the injection rate of hydrogen-rich media,H2 concentration,and oxygen enrichment rate of the blast on the temperature distribution were *** indicated that the increase in the injection rate of the hydrogen-rich media decreased the amount of direct reduction and led to an increase in the furnace ***,an increase in the oxygen enrichment rate led to a decrease in the furnace temperature,but could reduce the solid fuel ratio,while the change in H2 concentration had less effect on the temperature *** combination of hydrogen-rich media injection and the increase in the oxygen enrichment rate would help to adjust the temperature distribution to the same level as the conventional blast furnace conditions.

关键词： Heat distribution Blast furnace Low-carbon condition Hydrogen enrichment Calculation model

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Fractal Study on the Evolution of Micro-Pores in Concrete Under Freeze-Thaw

引用

Journal of Wuhan University of Technology(Materials Science) 2024年第1期39卷 109-117页

作者：孙浩然邹春霞 xu Deru GUO Xiaosong HUANG kun College of Water Conservancy and Civil Engineering Inner Mongolia Agricultural UniversityHohhot 010018China Xi’an HaiTang Vocational College Xi’an 710038China

After exposure to freeze-thaw cycles, scanning electron microscopy(SEM) and nuclear magnetic resonance(NMR) were used to test the four mixtures. The microstructure is qualitatively analyzed from the 2D SEM image and the 3D pore distribution curve before and after freezing and thawing. The fractal dimension is utilized to characterize the two-dimensional topography image and the three-dimensional pore distribution, quantitatively. The results reveal that the surface porosity and volume porosity increase as the freeze-thaw action increases. Self-similarity characteristics exist in micro-damage inside the concrete. In the fractal dimension, it is possible to characterize pore evolution quantitatively. The fractal dimension correlates with pore damage evolution. The fractal dimension effectively quantitatively characterizes micro-damage features at various scales from the local to the global level.

关键词： fractal dimension freeze-thaw cycle concrete SEM NMR

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：